1. Field of the Invention
The present invention relates to an image reading and recording apparatus composed of combining a recording unit and a scanner unit, and more particularly to a mechanism for opening and closing a scanner unit to a recording unit.
2. Description of the Related Art
There has been conventionally an image reading and recording apparatus composed of combining a recording apparatus and a scanner. The recording apparatus here records an image onto a recording material with a recording head based on image information. The scanner reads an image on an original with a reading unit, such as a CCD, and outputs the read image signal. An image reading and recording apparatus is generally adapted to mount a scanner unit on a recording unit, which is a recording apparatus, in the state capable of opening and closing the scanner unit. The image reading and recording apparatus is adapted to move the scanner unit upward for maintenance, such as an exchange of a recording head or an ink tank of the recording unit and a removal of jammed paper.
In the image reading and recording apparatus like this, the scanner unit capable of being opened and closed constitutes a cover unit capable of being opened and closed for covering an opened portion of a main body apparatus unit for performing the maintenance. At the time of performing a maintenance operation, it is necessary to open the scanner unit and to hold the scanner unit in the opened state. Consequently, an opening and closing mechanism for that is needed. Moreover, a mechanism for decelerating the cover unit for safety reasons lest the cover unit vigorously closes in process of closing the opened portion of the main body apparatus unit is also needed. Moreover, an assist mechanism for reducing an operating force at the time of opening the cover unit and a lock mechanism for locking the cover unit in a closed state are sometimes needed.
However, if these mechanisms are separately included, then the enlargement of the apparatus main body in size and an increase in cost owing to the increase of the number of parts are brought about. Accordingly, a mechanism was proposed which included the function of holding a cover unit in the opened state, the function of decelerating the cover unit in process of closing, the power assist function of reducing the operating force at the time of opening the cover unit, and the lock function of holding the cover unit in the closed state.
FIG. 7 is a side view illustrating a conventional image reading and recording apparatus in the state of closing a cover unit thereof. FIG. 8 is a side view illustrating the state of a damper unit when the cover unit is closed. FIG. 9 is a side view illustrating the state of the damper unit when the cover unit is opened. FIG. 10 is a side view illustrating the state of the damper unit in the process of opening the cover unit.
In FIGS. 7, 8, 9 and 10, a scanner unit 103 is attached to a frame 102 constituting the upper housing of a recording unit 120 with a rotating shaft 103b in the state capable of being opened and closed. A damper unit 110 is coupled between the frame 102 and the scanner unit 103. The damper unit 110 includes a holder 104 and a rod 105, which are assembled so that they each can slide in the expansion and contraction direction thereof, and a compression spring 108 mounted between the holder 104 and the rod 105 in a retractable state. The holder 104 is revolvably supported by a holding case 106, which is fixed to the frame 102, with a rotating shaft 104a. The rod 105 is coupled to a fitting hole 103a of the scanner unit 103 with a fitting shaft 105a at an end of the rod 105. The compression spring 108 operates on the rod 105 to extend the rod 105 to the left direction in FIG. 7.
As illustrated in FIG. 8, in the state in which the scanner unit 103 is closed, the fitting shaft 105a is pressed to the end of a depression portion 106a formed in the holding case 106 by the urging force of the spring 108. The scanner unit 103 is raised from this state to be revolved around the rotating shaft 103b. As illustrated in FIG. 10, the three points of the rotating shaft 104a of the holder 104, the fitting shaft 105a of the rod 105, and the rotating shaft 103b of the scanner unit 103 thereupon align on a straight line. When the scanner unit 103 moves across the position (switching position) further to the upper direction, the sliding force of the rod 105 owing to the reaction force of the spring 108 begins to operate on the scanner unit 103 to revolve to the upper direction. The moment caused by the operating force is gradually increasing. Consequently, the moment around the rotating shaft 103b owing to the weight of the scanner unit 103 is gradually reduced, and then the scanner unit 103 can be opened gradually by a smaller operating force.
In the state in which the scanner unit 103 is completely opened as illustrate in FIG. 9, the spring force of the spring 108 is set so that the moment around the rotating shaft 103b caused by the elastic force of the spring 108 may be larger than the moment caused by the self-weight of the scanner unit 103. By setting the spring force in this way, the scanner unit 103 can be held at the opened position thereof illustrated in FIG. 9 by the upward force of the rod 105 caused by the spring 108. In this state, a user can perform a desired maintenance operation through the opened portion of the upper part of the recording unit 120.
When the scanner unit 103 is being pushed down from the opened position of FIG. 9 to be closed, the scanner unit 103 reaches the switching position, where the rotating shaft 104a of the holder 104, the fitting shaft 105a of the rod 105, and the rotating shaft 103b of the scanner unit 103 align on the straight line as illustrated in FIG. 10, in the process of the closing. From the opened position to the arrival at the switching position, the reaction force of the spring 108 operates on the scanner unit 103 into the direction to open the scanner unit 103. Consequently, the damper unit 110 operates on the scanner unit 103 so as not to be rapidly closed.
When the scanner unit 103 is revolved into the closing direction across the switching position of FIG. 10, the reaction force of the spring 108 begins to operate on the scanner unit 103 into the closing direction thereof. The force into the closing direction becomes larger as the scanner unit 103 approaches the closed position illustrated in FIG. 8. Consequently, the scanner unit 103 is accelerated into rapid closing direction, and a shock operating on the recording unit 120 when the scanner unit 103 is closed becomes large.
The holding case 106 having the aforesaid depression portion 106a receiving the fitting shaft 105a of the rod 105 is provided for preventing such a shock. That is, the holding case 106 is adapted so that the fitting shaft 105a of the rod 105 abuts against the inner part of the depression portion 106a of the holding case 106 in the neighborhood of the switching position where the operating direction of the spring 108 is switched. By the abutting against the inner part of the depression portion 106a, the force operating on the scanner unit 103 into the closing direction thereof is dispersed, and the scanner unit 103 is decelerated while moving to the closed position of FIG. 8. In the closed state of the scanner unit 103, the reaction force of the spring 108 operates on the scanner unit 103 through the rod 105 so as to press the scanner unit 103 downward. Consequently, the scanner unit 103 is held in a locked state at the closed position thereof by the holding of the fitting shaft 105a of the damper unit 110 in the depression portion 106a of the holding case 106.
However, in the configuration mentioned above, when the weight of the scanner unit 103 becomes large, the urging force of the spring 108 of the damper unit 110 is needed to be accordingly increased in order to hold the scanner unit 103 in the opened state. If the operating force into the opening direction is increased, the force into the closing direction is also increased similarly. Consequently, the aforesaid method of dispersing the spring force by abutting the fitting shaft 105a of the rod 105 against the depression portion 106a of the holding case 106 cannot obtain a necessary and sufficient buffering effect. That is, the buffering effect sufficient for fully decreasing the speed of the scanner unit at the time of closing the scanner unit cannot be obtained, and the scanner unit ends up colliding with the recording unit at a considerable speed. Consequently, it has been difficult to reduce or avoid the shock at the closed position.
In such a situation, there is a disadvantage that a user gets his or her hand stuck in the scanner unit 103 or that the apparatus is damaged by the vigorous moving of the scanner unit 103 up to the closed position thereof. Moreover, if another buffering unit for buffering the movement of the scanner unit 103 before the closed position thereof is provided in order to avoid the disadvantage like this, then there arises the disadvantage that enlargement in size of the apparatus main body and the increase in cost of the apparatus are bring about.